Physics for Leaving Cert Students

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“Colour” is a property of subatomic particles, a lot like electrical charge. It has absolutely nothing to do with colour in the normal sense. Just as charge leads to interactions via electromagnetic forces, so colour leads to interactions via so-called strong forces.

Taking that back another step: there are four fundamental forces of nature. The two of them that you are extremely familiar with are the electromagnetic and gravitational forces. These are long-range forces; they act over large distances. The other two, the weak and strong forces, act on the atomic and subatomic scale, so you only encounter their effects in a very indirect way. The strong force is particularly important as it’s the force that sticks the protons and neutrons in the nuclei of atoms together. (You wouldn’t otherwise expect nuclei to stick together; the electromagnetic interactions are between positively…

It divides the fundamental particles into three families, the quarks, the leptons and the gauge bosons… and one loner, the Higgs Boson.

There are six different quarks, which get organised into three pairs because their properties follow a bit of a pattern.

They have slightly odd names: up & down, charm & strange, and top & bottom.

Quarks have electric charges, so they make and are affected by electric fields. Oddly, though, the size of their electric charges is one or two thirds of the size of the electric charge on an electron.

(Up, charm and top quarks have a charge of +2/3 , down, strange, and bottom quarks have a charge of -1/3.)

Quarks have a mass. If you could somehow get them to sit still and get on a…